test(host-environment): cover cj/match-localtime-to-zoneinfo

1 files changed, 58 insertions, 0 deletions

diff --git a/tests/test-host-environment-match-localtime.el b/tests/test-host-environment-match-localtime.el
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+++ b/tests/test-host-environment-match-localtime.el
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+;;; test-host-environment-match-localtime.el --- Tests for cj/match-localtime-to-zoneinfo -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Sibling tests cover the predicates and `cj/detect-system-timezone'.
+;; `cj/match-localtime-to-zoneinfo' (the file-comparison path that's
+;; tried first by detect-system-timezone) was uncovered.
+;;
+;; The function hits two hard-coded paths (`/etc/localtime' and
+;; `/usr/share/zoneinfo').  Stubbing `file-exists-p' / `file-directory-p'
+;; via `cl-letf' on a native-comp build of Emacs triggers trampoline
+;; install errors, so we let the function touch the real filesystem
+;; and only assert on the contract (string-or-nil, string lives under
+;; the zoneinfo directory).
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'host-environment)
+
+;;; cj/match-localtime-to-zoneinfo
+
+(ert-deftest test-host-environment-match-localtime-returns-string-or-nil ()
+  "Normal: the function returns either a string (a zoneinfo-relative path)
+or nil.  On any reasonable Linux box `/etc/localtime' is a copy of one
+of the files under `/usr/share/zoneinfo', so we expect a string here;
+on systems missing either path we still want the function to not
+crash, so accept nil as well."
+  (let ((result (cj/match-localtime-to-zoneinfo)))
+    (should (or (null result) (stringp result)))
+    (when (stringp result)
+      ;; The returned path should have its prefix stripped — no leading
+      ;; "/usr/share/zoneinfo/" in the result.
+      (should-not (string-prefix-p "/usr/share/zoneinfo/" result))
+      ;; And the resolved file under zoneinfo should actually exist.
+      (should (file-exists-p (expand-file-name result "/usr/share/zoneinfo"))))))
+
+(ert-deftest test-host-environment-match-localtime-result-matches-localtime-bytes ()
+  "Normal: when the function returns a path, its file content matches
+`/etc/localtime' byte-for-byte (that's the function's whole job)."
+  (skip-unless (and (file-exists-p "/etc/localtime")
+                    (file-directory-p "/usr/share/zoneinfo")))
+  (let ((result (cj/match-localtime-to-zoneinfo)))
+    (when (stringp result)
+      (let ((matched-path (expand-file-name result "/usr/share/zoneinfo"))
+            (read-bytes
+             (lambda (p)
+               (with-temp-buffer
+                 (set-buffer-multibyte nil)
+                 (insert-file-contents-literally p)
+                 (buffer-string)))))
+        (should (equal (funcall read-bytes "/etc/localtime")
+                       (funcall read-bytes matched-path)))))))
+
+(provide 'test-host-environment-match-localtime)
+;;; test-host-environment-match-localtime.el ends here